MarsSeed [1] filed a deletion request for pantheon-mail-git [2]: Not useful to keep this long unmaintained, 3-years-broken VCS package. Upstream is not very actively maintained: it receives mostly minor translation and CI bumps. They publish stable tags with adequate frequency. Extra repo carries the latest stable release.
[1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/pantheon-mail-git/
